Impact of Measurement Noise on Genetic Association Studies of Cardiac Function.

Recent research has effectively used quantitative traits from imaging to boost the capabilities of genome-wide association studies (GWAS), providing further understanding of disease biology and various traits. However, it's important to note that phenotyping inherently carries measurement error and noise that could influence subsequent genetic analyses. The study focused on left ventricular ejection fraction (LVEF), a vital yet potentially inaccurate quantitative measurement, to investigate how imprecision in phenotype measurement affects genetic studies. Several methods of acquiring LVEF, along with simulating measurement noise, were assessed for their effects on ensuing genetic analyses. The results showed that by introducing just 7.9% of measurement noise, all genetic associations in an LVEF GWAS with almost forty thousand individuals could be eliminated. Moreover, a 1% increase in mean absolute error (MAE) in LVEF had an effect equivalent to a 10% reduction in the sample size of the cohort on the power of GWAS. Therefore, enhancing the accuracy of phenotyping is crucial to maximize the effectiveness of genome-wide association studies.

Diagnostic potential of energy metabolism-related genes in heart failure with preserved ejection fraction.

Background: Heart failure with preserved ejection fraction (HFpEF) is associated with changes in cardiac metabolism that affect energy supply in the heart. However, there is limited research on energy metabolism-related genes (EMRGs) in HFpEF. Methods: The HFpEF mouse dataset (GSE180065, containing heart tissues from 10 HFpEF and five control samples) was sourced from the Gene Expression Omnibus database. Gene expression profiles in HFpEF and control groups were compared to identify differentially expressed EMRGs (DE-EMRGs), and the diagnostic biomarkers with diagnostic value were screened using machine learning algorithms. Meanwhile, we constructed a biomarker-based nomogram model for its predictive power, and functionality of diagnostic biomarkers were conducted using single-gene gene set enrichment analysis, drug prediction, and regulatory network analysis. Additionally, consensus clustering analysis based on the expression of diagnostic biomarkers was utilized to identify differential HFpEF-related genes (HFpEF-RGs). Immune microenvironment analysis in HFpEF and subtypes were performed for analyzing correlations between immune cells and diagnostic biomarkers as well as HFpEF-RGs. Finally, qRT-PCR analysis on the HFpEF mouse model was used to validate the expression levels of diagnostic biomarkers. Results: We selected 5 biomarkers (Chrna2, Gnb3, Gng7, Ddit4l, and Prss55) that showed excellent diagnostic performance. The nomogram model we constructed demonstrated high predictive power. Single-gene gene set enrichment analysis revealed enrichment in aerobic respiration and energy derivation. Further, various miRNAs and TFs were predicted by Gng7, such as Gng7-mmu-miR-6921-5p, ETS1-Gng7. A lot of potential therapeutic targets were predicted as well. Consensus clustering identified two distinct subtypes of HFpEF. Functional enrichment analysis highlighted the involvement of DEGs-cluster in protein amino acid modification and so on. Additionally, we identified five HFpEF-RGs (Kcnt1, Acot1, Kcnc4, Scn3a, and Gpam). Immune analysis revealed correlations between Macrophage M2, T cell CD4+ Th1 and diagnostic biomarkers, as well as an association between Macrophage and HFpEF-RGs. We further validated the expression trends of the selected biomarkers through experimental validation. Conclusion: Our study identified 5 diagnostic biomarkers and provided insights into the prediction and treatment of HFpEF through drug predictions and network analysis. These findings contribute to a better understanding of HFpEF and may guide future research and therapy development.

Genome-Wide Association Study of Beta-Blocker Survival Benefit in Black and White Patients with Heart Failure with Reduced Ejection Fraction.

In patients with heart failure with reduced ejection fraction (HFrEF), individual responses to beta-blockers vary. Candidate gene pharmacogenetic studies yielded significant but inconsistent results, and they may have missed important associations. Our objective was to use an unbiased genome-wide association study (GWAS) to identify loci influencing beta-blocker survival benefit in HFrEF patients. Genetic variant × beta-blocker exposure interactions were tested in Cox proportional hazards models for all-cause mortality stratified by self-identified race. The models were adjusted for clinical risk factors and propensity scores. A prospective HFrEF registry (469 black and 459 white patients) was used for discovery, and linkage disequilibrium (LD) clumped variants with a beta-blocker interaction of p < 5 × 10-5, were tested for Bonferroni-corrected validation in a multicenter HFrEF clinical trial (288 black and 579 white patients). A total of 229 and 18 variants in black and white HFrEF patients, respectively, had interactions with beta-blocker exposure at p < 5 × 10-5 upon discovery. After LD-clumping, 100 variants and 4 variants in the black and white patients, respectively, remained for validation but none reached statistical significance. In conclusion, genetic variants of potential interest were identified in a discovery-based GWAS of beta-blocker survival benefit in HFrEF patients, but none were validated in an independent dataset. Larger cohorts or alternative approaches, such as polygenic scores, are needed.

Prevalence and prognosis of genetically proven familial hypercholesterolemia in subjects with coronary artery disease and reduced ejection fraction.

Few studies have genetically screened variants related to familial hypercholesterolemia (FH) and investigated their survival impact in patients with coronary artery disease (CAD) and reduced left ventricular ejection fraction (EF). Patients with CAD and reduced EF (< 40%) were enrolled. Their genomic DNAs were sequenced for FH-related genes. All-cause and cardiovascular mortality data served as the major outcome. A total of 256 subjects were analyzed and 12 subjects (4.7%) carried FH-related genetic variants. After a median follow-up period of 44 months, 119 of the study subjects died. Cox survival analysis showed that carrying the FH genetic variant did not have a significant impact on the survival of CAD with reduced EF. However, higher estimated glomerular filtration rate (eGFR), better EF and beta blocker use were protective for a lower all-cause mortality. Further larger studies are needed to evaluate the impact of carrying the FH-related genetic variant on survival of CAD with reduced EF.

Tissue inhibitor of metalloproteinase-4 deletion in mice impacts maternal cardiac function during pregnancy and postpartum.

Reversible physiological cardiac hypertrophy of the maternal heart occurs during pregnancy and involves extracellular matrix (ECM) remodeling. Previous mouse studies revealed that changes in ECM molecules accompany functional changes in the left ventricle (LV) during late pregnancy and postpartum. We evaluated the effect of global Timp4 deletion in female mice on LV functional parameters and ECM molecules during pregnancy and the postpartum period. Heart weights normalized to tibia lengths were increased in Timp4 knockout (Timp4 KO) virgin, pregnant, and postpartum day 2 mice compared with wild types. Serial echocardiography performed on pregnancy days 10, 12, and 18 and postpartum days (ppds) 2, 7, 14, 21, and 28 revealed that both wild-type and Timp4 KO mice increased end systolic and end diastolic volumes (ESV, EDV) by mid to late pregnancy compared with virgins, with EDV changes persisting through the postpartum period. When compared with wild types, Timp4 KO mice exhibited higher ejection fractions in virgins, at pregnancy days 10 and 18 and ppd2 and ppd14. High-molecular weight forms of COL1A1 and COL3A1 proteins in LV were greater in Timp4 KO virgins, and COL1A1 was higher in late pregnancy and on ppd2 compared with wild types. With exceptions, Timp4 KO mice during late pregnancy and the early postpartum period were able to maintain stroke volume similar to wild-type mice through increased ejection fraction. Although TIMP4 deletion in females exhibited altered ECM molecules, it did not adversely affect cardiac function during first pregnancies and lactation.NEW & NOTEWORTHY Pregnancy and lactation increase volume load on the heart. Defects in cardiac remodeling during pregnancy and postpartum can result in peripartum cardiomyopathy. TIMPs participate in cardiac remodeling. The present study reports the cardiac function in Timp4 knockout adult female mice during pregnancy and lactation. Timp4 knockout females at many time points have higher ejection fraction to maintain stroke volume. Global deletion of Timp4 was not detrimental to maternal heart function during first pregnancies and lactation.

Genetic architecture of heart failure with preserved versus reduced ejection fraction.

Pharmacologic clinical trials for heart failure with preserved ejection fraction have been largely unsuccessful as compared to those for heart failure with reduced ejection fraction. Whether differences in the genetic underpinnings of these major heart failure subtypes may provide insights into the disparate outcomes of clinical trials remains unknown. We utilize a large, uniformly phenotyped, single cohort of heart failure sub-classified into heart failure with reduced and with preserved ejection fractions based on current clinical definitions, to conduct detailed genetic analyses of the two heart failure sub-types. We find different genetic architectures and distinct genetic association profiles between heart failure with reduced and with preserved ejection fraction suggesting differences in underlying pathobiology. The modest genetic discovery for heart failure with preserved ejection fraction (one locus) compared to heart failure with reduced ejection fraction (13 loci) despite comparable sample sizes indicates that clinically defined heart failure with preserved ejection fraction likely represents the amalgamation of several, distinct pathobiological entities. Development of consensus sub-phenotyping of heart failure with preserved ejection fraction is paramount to better dissect the underlying genetic signals and contributors to this highly prevalent condition.

Knockout of Trpa1 accelerates age-related cardiac fibrosis and dysfunction.

Age-related cardiac fibrosis contributes to the development of heart failure with preserved ejection fraction which lacks ideal treatment. Transient receptor potential ankyrin 1 (TRPA1) is an oxidative stress sensor and could attenuate age-related pathologies in invertebrates. The present study aimed to test whether TRPA1 plays a role in age-related cardiac remodeling and dysfunction. The cardiac function and pathology of 12-week-old (young) and 52-week-old (older) Trpa1-/- mice and wild-type (WT) littermates were evaluated by echocardiography and histologic analyses. The expression levels of 84 fibrosis-related genes in the heart were measured by quantitative polymerase chain reaction array. Young Trpa1-/- and WT mice had similar left ventricular wall thickness, volume, and systolic and diastolic function. Older Trpa1-/- mice had significantly increased left ventricular internal diameter and volume and impaired systolic (lower left ventricular ejection fraction) and diastolic (higher E/A ratio and isovolumetric relaxation time) functions compared with older WT mice (P<0.05 or P<0.01). Importantly, older Trpa1-/- mice had enhanced cardiac fibrosis than older WT mice (P<0.05) while the two strains had similar degree of cardiac hypertrophy. Among the 84 fibrosis-related genes, Acta2, Inhbe, Ifng, and Ccl11 were significantly upregulated, while Timp3, Stat6, and Ilk were significantly downregulated in the heart of older Trpa1-/- mice compared with older WT mice. Taken together, we found that knocking out Trpa1 accelerated age-related myocardial fibrosis, ventricular dilation, and cardiac dysfunction. These findings suggest that TRPA1 may become a therapeutic target for preventing and/or treating cardiac fibrosis and heart failure with preserved ejection fraction in the elderly.

Exosomal microRNAs miR-30d-5p and miR-126a-5p Are Associated with Heart Failure with Preserved Ejection Fraction in STZ-Induced Type 1 Diabetic Rats.

Exosomal microRNAs (EXO-miRNAs) are promising non-invasive diagnostic biomarkers for cardiovascular disease. Heart failure with preserved ejection fraction (HFpEF) is a poorly understood cardiovascular complication of diabetes mellitus (DM). Little is known about whether EXO-miRNAs can be used as biomarkers for HFpEF in DM. We aimed to investigate the relationship between EXO-miRNAs and HFpEF in STZ-induced diabetic rats. We prepared STZ-induced diabetic rats exhibiting a type 1 DM phenotype with low body weight, hyperglycemia, hyperlipidemia and hypoinsulinemia. Histological sections confirmed atrophy and fibrosis of the heart, with collagen accumulation representing diabetic cardiomyopathy. Significant decreases in end-diastolic volume, stroke volume, stroke work, end-systolic elastance and cardiac output indicated impaired cardiac contractility, as well as mRNA conversion of two isoforms of myosin heavy chain (α-MHC and ß-MHC) and increased atrial natriuretic factor (ANF) mRNA indicating heart failure, were consistent with the features of HFpEF. In diabetic HFpEF rats, we examined a selected panel of 12 circulating miRNAs associated with HF (miR-1-3p, miR-21-5p, miR-29a-5p, miR-30d-5p, miR-34a-5p, miR-126a-5p, miR-143-3p, miR-145-5p, miR-195-5p, miR-206-3p, miR-320-3p and miR-378-3p). Although they were all expressed at significantly lower levels in the heart compared to non-diabetic controls, only six miRNAs (miR-21-5p, miR-30d-5p, miR-126a-5p, miR-206-3p, miR-320-3p and miR-378-3p) were also reduced in exosomal content, while one miRNA (miR-34a-5p) was upregulated. Similarly, although all miRNAs were correlated with reduced cardiac output as a measure of cardiovascular performance, only three miRNAs (miR-30d-5p, miR-126a-5p and miR-378-3p) were correlated in exosomal content. We found that miR-30d-5p and miR-126a-5p remained consistently correlated with significant reductions in exosomal expression, cardiac expression and cardiac output. Our findings support their release from the heart and association with diabetic HFpEF. We propose that these two EXO-miRNAs may be important for the development of diagnostic tools for diabetic HFpEF.

Sex differences in heart mitochondria regulate diastolic dysfunction.

Heart failure with preserved ejection fraction (HFpEF) exhibits a sex bias, being more common in women than men, and we hypothesize that mitochondrial sex differences might underlie this bias. As part of genetic studies of heart failure in mice, we observe that heart mitochondrial DNA levels and function tend to be reduced in females as compared to males. We also observe that expression of genes encoding mitochondrial proteins are higher in males than females in human cohorts. We test our hypothesis in a panel of genetically diverse inbred strains of mice, termed the Hybrid Mouse Diversity Panel (HMDP). Indeed, we find that mitochondrial gene expression is highly correlated with diastolic function, a key trait in HFpEF. Consistent with this, studies of a "two-hit" mouse model of HFpEF confirm that mitochondrial function differs between sexes and is strongly associated with a number of HFpEF traits. By integrating data from human heart failure and the mouse HMDP cohort, we identify the mitochondrial gene Acsl6 as a genetic determinant of diastolic function. We validate its role in HFpEF using adenoviral over-expression in the heart. We conclude that sex differences in mitochondrial function underlie, in part, the sex bias in diastolic function.

A deep learning model for early risk prediction of heart failure with preserved ejection fraction by DNA methylation profiles combined with clinical features.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF), affected collectively by genetic and environmental factors, is the common subtype of chronic heart failure. Although the available risk assessment methods for HFpEF have achieved some progress, they were based on clinical or genetic features alone. Here, we have developed a deep learning framework, HFmeRisk, using both 5 clinical features and 25 DNA methylation loci to predict the early risk of HFpEF in the Framingham Heart Study Cohort. RESULTS: The framework incorporates Least Absolute Shrinkage and Selection Operator and Extreme Gradient Boosting-based feature selection, as well as a Factorization-Machine based neural network-based recommender system. Model discrimination and calibration were assessed using the AUC and Hosmer-Lemeshow test. HFmeRisk, including 25 CpGs and 5 clinical features, have achieved the AUC of 0.90 (95% confidence interval 0.88-0.92) and Hosmer-Lemeshow statistic was 6.17 (P = 0.632), which outperformed models with clinical characteristics or DNA methylation levels alone, published chronic heart failure risk prediction models and other benchmark machine learning models. Out of them, the DNA methylation levels of two CpGs were significantly correlated with the paired transcriptome levels (R < -0.3, P < 0.05). Besides, DNA methylation locus in HFmeRisk were associated with intercellular signaling and interaction, amino acid metabolism, transport and activation and the clinical variables were all related with the mechanism of occurrence of HFpEF. Together, these findings give new evidence into the HFmeRisk model. CONCLUSION: Our study proposes an early risk assessment framework for HFpEF integrating both clinical and epigenetic features, providing a promising path for clinical decision making.

Circulating miR-499a and miR-125b as Potential Predictors of Left Ventricular Ejection Fraction Improvement after Cardiac Resynchronization Therapy.

Cardiac resynchronization therapy represents a therapeutic option for heart failure drug-refractory patients. However, due to the lack of success in 30% of the cases, there is a demand for an in-depth analysis of individual heterogeneity. In this study, we aimed to evaluate the prognostic value of circulating miRNA differences. Responder patients were defined by a composite endpoint of the presence of left ventricular reverse remodelling (a reduction ≥15% in telesystolic volume and an increment ≥10% in left ventricular ejection fraction). Circulating miRNAs signature was analysed at the time of the procedure and at a 6-month follow-up. An expression analysis showed, both at baseline and at follow-up, differences between responders and non-responders. Responders presented lower baseline expressions of miR-499, and at follow-up, downregulation of miR-125b-5p, both associated with a significant improvement in left ventricular ejection fraction. The miRNA profile differences showed a marked sensitivity to distinguish between responders and non-responders. Our data suggest that miRNA differences might contribute to prognostic stratification of patients undergoing cardiac resynchronization therapy and suggest that preimplant cardiac context as well as remodelling response are key to therapeutic success.

Genotype-phenotype correlation in arrhythmogenic right ventricular cardiomyopathy-risk of arrhythmias and heart failure.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is predominantly caused by desmosomal genetic variants, and clinical hallmarks include arrhythmias and systolic dysfunction. We aimed at studying the impact of the implicated gene(s) on the disease course. METHODS: The Nordic ARVC Registry holds data on a multinational cohort of ARVC families. The effects of genotype on electrocardiographic features, imaging findings and clinical events were analysed. RESULTS: We evaluated 419 patients (55% men), with a mean follow-up of 11.2±7.4 years. A pathogenic desmosomal variant was identified in 62% of the 230 families: PKP2 in 41%, DSG2 in 13%, DSP in 7% and DSC2 in 3%. Reduced left ventricular ejection fraction (LVEF) ≤45% on cardiac MRI was more frequent among patients with DSC2/DSG2/DSP than PKP2 ARVC (27% vs 4%, p<0.01). In contrast, in Cox regression modelling of patients with definite ARVC, we found a higher risk of arrhythmias among PKP2 than DSC2/DSG2/DSP carriers: HR 0.25 (0.10-0.68, p<0.01) for atrial fibrillation/flutter, HR 0.67 (0.44-1.0, p=0.06) for ventricular arrhythmias and HR 0.63 (0.42-0.95, p<0.05) for any arrhythmia. Gene-negative patients had an intermediate risk (16%) of LVEF ≤45% and a risk of the combined arrhythmic endpoint comparable with DSC2/DSG2/DSP carriers. Male sex was a risk factor for both arrhythmias and reduced LVEF across all genotype groups (p<0.01). CONCLUSION: In this large cohort of ARVC families with long-term follow-up, we found PKP2 genotype to be more arrhythmic than DSC2/DSG2/DSP or gene-negative carrier status, whereas reduced LVEF was mostly seen among DSC2/DSG2/DSP carriers. Male sex was associated with a more severe phenotype.

Long non-coding RNA lincRNA-erythroid prosurvival attenuates inflammation by enhancing myosin heavy chain 6 stability through recruitment of heterogeneous nuclear ribonucleoprotein L in myocardial infarction.

Myocardial infarction (MI), a prevalent cardiac disorder with high mortality, leads to severe heart injury associated with inflammation and cardiomyocyte apoptosis. Long non-coding RNAs have been widely found to participate in the progression of MI. Here, we aimed to explore the impact of lincRNA-erythroid prosurvival (EPS) on MI-induced inflammation and cardiomyocyte apoptosis. Significantly, lincRNA-EPS was lowly expressed in MI mice and in oxygen and glucose deprivation (OGD)-treated HL-1 cells. Echocardiography analysis revealed that lincRNA-EPS overexpression increased left ventricular ejection fraction and left ventricular fraction shortening, and decreased left ventricular internal diameter at end systole and left ventricular internal diameter at end diastole in a mouse model. In our study, the expression levels of interleukin-6, tumor necrosis factor-alpha, interleukin-1ß, and interleukin-18 were upregulated in the MI mice and OGD-treated HL-1 cells, while lincRNA-EPS overexpression reversed these phenotypes. Meanwhile, lincRNA-EPS reduced MI-induced cardiomyocyte apoptosis in vivo and in vitro. Mechanically, lincRNA-EPS interacted with myosin heavy chain 6 (MYH6) and heterogeneous nuclear ribonucleoprotein L (HNRNPL), and the depletion of lincRNA-EPS and HNRNPL inhibited MYH6 mRNA stability in HL-1 cells. HNRNPL knockdown blocked lincRNA-EPS overexpression-induced MYH6 expression in the system. The depletion of MYH6 and HNRNPL could rescue lincRNA-EPS overexpression-reduced inflammation and apoptosis in HL-1 cells. Thus, we conclude that lincRNA-EPS attenuates inflammation and apoptosis in MI-induced myocardial injury by maintaining MYH6 stability through the recruitment of HNRNPL.

Identification of SCN5a p.C335R Variant in a Large Family with Dilated Cardiomyopathy and Conduction Disease.

INTRODUCTION: Familial dilated cardiomyopathy (DCM) is clinically variable and has been associated with mutations in more than 50 genes. Rapid improvements in DNA sequencing have led to the identification of diverse rare variants with unknown significance (VUS), which underlines the importance of functional analyses. In this study, by investigating human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), we evaluated the pathogenicity of the p.C335R sodium voltage-gated channel alpha subunit 5 (SCN5a) variant in a large family with familial DCM and conduction disease. METHODS: A four-generation family with autosomal dominant familial DCM was investigated. Next-generation sequencing (NGS) was performed in all 16 family members. Clinical deep phenotyping, including endomyocardial biopsy, was performed. Skin biopsies from two patients and one healthy family member were used to generate human-induced pluripotent stem cells (iPSCs), which were then differentiated into cardiomyocytes. Patch-clamp analysis with Xenopus oocytes and iPSC-CMs were performed. RESULTS: A SCN5a variant (c.1003T>C; p.C335R) could be detected in all family members with DCM or conduction disease. A novel truncating TTN variant (p.Ser24998LysfsTer28) could also be identified in two family members with DCM. Family members with the SCN5a variant (p.C335R) showed significantly longer PQ and QRS intervals and lower left ventricular ejection fractions (LV-EF). All four patients who received CRT-D were non-responders. Electrophysiological analysis with Xenopus oocytes showed a loss of function in SCN5a p.C335R. Na+ channel currents were also reduced in iPSC-CMs from DCM patients. Furthermore, iPSC-CM with compound heterozygosity (SCN5a p.C335R and TTNtv) showed significant dysregulation of sarcomere structures, which may be contributed to the severity of the disease and earlier onset of DCM. CONCLUSION: The SCN5a p.C335R variant is causing a loss of function of peak INa in patients with DCM and cardiac conduction disease. The co-existence of genetic variants in channels and structural genes (e.g., SCN5a p.C335R and TTNtv) increases the severity of the DCM phenotype.

Shorter (GT)n repeats in the haem-oxygenase 1 gene promoter are associated with better mid-term survival in subjects with coronary artery disease and abnormal ejection fraction.

BACKGROUND: Haem oxygenase (HO)-1 is a rate-limiting enzyme for degrading haem into carbon monoxide. Subjects with longer GT repeats in the HO-1 gene (HMOX1) promoter are more likely to have coronary artery disease (CAD) and cardiovascular events. METHODS: We retrospectively enrolled CAD subjects with an abnormal ejection fraction (EF) <50% from our catheterisation data (N = 670). Polymerase chain reactions were performed for amplifying the HMOX1 promoter GT repeating segment to determine the number of repeats. RESULTS: In a median follow-up period of 40 months, 213 patients died. The distribution of genotype for HMOX1 promoter GT repeating segments SS, SL, and LL were significantly different (p < 0.001) between the dead (44.6%, 36.2%, 19.2%, respectively) and the survived (53.8%, 37.4%, 8.8%, respectively) (S allele: ≤30 repeats, L allele: >30 repeats). In Cox regression analysis, carrier of S allele (hazard ratio 0.665, p = 0.027), a higher EF (hazard ratio 0.037, p = 0.001), and revascularization with PCI were all negatively associated with all-cause death in subjects with CAD and abnormal EF. CONCLUSIONS: Carrier of shorter (GT)n repeats of HMOX1 gene promoter was negatively correlated with death events in CAD patients with abnormal EF.

Association of Genetic Variants With Outcomes in Patients With Nonischemic Dilated Cardiomyopathy.

BACKGROUND: The clinical relevance of genetic variants in nonischemic dilated cardiomyopathy (DCM) is unsettled. OBJECTIVES: The study sought to assess the prognostic impact of disease-causing genetic variants in DCM. METHODS: Baseline and longitudinal clinical data from 1,005 genotyped DCM probands were retrospectively collected at 20 centers. A total of 372 (37%) patients had pathogenic or likely pathogenic variants (genotype positive) and 633 (63%) were genotype negative. The primary endpoint was a composite of major adverse cardiovascular events. Secondary endpoints were end-stage heart failure (ESHF), malignant ventricular arrhythmia (MVA), and left ventricular reverse remodeling (LVRR). RESULTS: After a median follow-up of 4.04 years (interquartile range: 1.70-7.50 years), the primary endpoint had occurred in 118 (31.7%) patients in the genotype-positive group and in 125 (19.8%) patients in the genotype-negative group (hazard ratio [HR]: 1.51; 95% confidence interval [CI]: 1.17-1.94; P = 0.001). ESHF occurred in 60 (16.1%) genotype-positive patients and in 55 (8.7%) genotype-negative patients (HR: 1.67; 95% CI: 1.16-2.41; P = 0.006). MVA occurred in 73 (19.6%) genotype-positive patients and in 77 (12.2%) genotype-negative patients (HR: 1.50; 95% CI: 1.09-2.07; P = 0.013). LVRR occurred in 39.6% in the genotype-positive group and in 46.2% in the genotype-negative group (P = 0.047). Among individuals with baseline left ventricular ejection fraction ≤35%, genotype-positive patients exhibited more major adverse cardiovascular events, ESHF, and MVA than their genotype-negative peers (all P < 0.02). LVRR and clinical outcomes varied depending on the underlying affected gene. CONCLUSIONS: In this study, DCM patients with pathogenic or likely pathogenic variants had worse prognosis than genotype-negative individuals. Clinical course differed depending on the underlying affected gene.

Cardiomyocyte-specific miR-100 overexpression preserves heart function under pressure overload in mice and diminishes fatty acid uptake as well as ROS production by direct suppression of Nox4 and CD36.

MicroRNAs are key regulators of the cardiac response to injury. MiR-100 has recently been suggested to be involved in different forms of heart failure, but functional studies are lacking. In the present study, we examined the impact of transgenic miR-100 overexpression on cardiac structure and function during physiological aging and pathological pressure-overload-induced heart failure in mice after transverse aortic constriction surgery. MiR-100 was moderately upregulated after induction of pressure overload in mice. While in our transgenic model the cardiomyocyte-specific overexpression of miR-100 did not result in an obvious cardiac phenotype in unchallenged mice, the transgenic mouse strain exhibited less left ventricular dilatation and a higher ejection fraction than wildtype animals, demonstrating an attenuation of maladaptive cardiac remodeling by miR-100. Cardiac transcriptome analysis identified a repression of several regulatory genes related to cardiac metabolism, lipid peroxidation, and production of reactive oxygen species (ROS) by miR-100 overexpression, possibly mediating the observed functional effects. While the modulation of ROS-production seemed to be indirectly affected by miR-100 via Alox5-and Nox4-downregulation, we demonstrated that miR-100 induced a direct repression of the scavenger protein CD36 in murine hearts resulting in a decreased uptake of long-chain fatty acids and an alteration of mitochondrial respiratory function with an enhanced glycolytic state. In summary, we identified miR-100 as a modulator of cardiac metabolism and ROS production without an apparent cardiac phenotype at baseline but a protective effect under conditions of pressure-overload-induced cardiac stress, providing new insight into the mechanisms of heart failure.

miR155 Deficiency Reduces Myofibroblast Density but Fails to Improve Cardiac Function after Myocardial Infarction in Dyslipidemic Mouse Model.

Myocardial infarction remains the most common cause of heart failure with adverse remodeling. MicroRNA (miR)155 is upregulated following myocardial infarction and represents a relevant regulatory factor for cardiac remodeling by engagement in cardiac inflammation, fibrosis and cardiomyocyte hypertrophy. Here, we investigated the role of miR155 in cardiac remodeling and dysfunction following myocardial infarction in a dyslipidemic mouse model. Myocardial infarction was induced in dyslipidemic apolipoprotein E-deficient (ApoE-/-) mice with and without additional miR155 knockout by ligation of the LAD. Four weeks later, echocardiography was performed to assess left ventricular (LV) dimensions and function, and mice were subsequently sacrificed for histological analysis. Echocardiography revealed no difference in LV ejection fractions, LV mass and LV volumes between ApoE-/- and ApoE-/-/miR155-/- mice. Histology confirmed comparable infarction size and unaltered neoangiogenesis in the myocardial scar. Notably, myofibroblast density was significantly decreased in ApoE-/-/miR155-/- mice compared to the control, but no difference was observed for total collagen deposition. Our findings reveal that genetic depletion of miR155 in a dyslipidemic mouse model of myocardial infarction does not reduce infarction size and consecutive heart failure but does decrease myofibroblast density in the post-ischemic scar.

Variant Reinterpretation in Survivors of Cardiac Arrest With Preserved Ejection Fraction (the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry) by Clinicians and Clinical Commercial Laboratories.

BACKGROUND: Following an unexplained cardiac arrest, clinical genetic testing is increasingly becoming standard of care. Periodic review of variant classification is required, as reinterpretation can change the diagnosis, prognosis, and management of patients and their relatives. METHODS: This study aimed to develop and validate a standardized algorithm to facilitate clinical application of the 2015 American College of Medical Genetics and Association for Molecular Pathology guidelines for the interpretation of genetic variants. The algorithm was applied to genetic results in the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry, to assess the rate of variant reclassification over time. Variant classifications were then compared with the classifications of 2 commercial laboratories to determine the rate and identify sources of variant interpretation discordance. RESULTS: Thirty-one percent of participants (40 of 131) had at least 1 genetic variant with a clinically significant reclassification over time. Variants of uncertain significance were more likely to be downgraded (73%) to benign than upgraded to pathogenic (27%; P=0.03). For the second part of the study, 50% (70 of 139) of variants had discrepant interpretations (excluding benign variants), provided by at least 1 team. CONCLUSIONS: Periodic review of genetic variant classification is a key component of follow-up care given rapidly changing information in the field. There is potential for clinical care gaps with discrepant variant interpretations, based on the interpretation and application of current guidelines. The development of gene- and disease-specific guidelines and algorithms may provide an opportunity to further standardize variant interpretation reporting in the future. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00292032.

Knockdown of ZFAS1 improved the cardiac function of myocardial infarction rats via regulating Wnt/ß-catenin signaling pathway.

Myocardial infarction (MI) is a big health threat in the world, and it is characterized by high morbidity and mortality. However, current treatments are not effective enough, and novel therapeutic strategies need to be explored. ZFAS1 has been proved to be involved in the regulation of MI, but the specific mechanism remains unclear. MI rats were constructed through left anterior descending artery ligation, and hypoxia cell model was also established. The proliferation, invasion, and migration of cells were detected via CCK8, traswell, and wound healing methods. Immunohistochemistry staining, western blotting, and qRT-PCR were used to detect the levels of molecules. Knockdown of ZFAS1 significantly increased the proliferation, migration, and invasion of cardiac fibroblasts. Knockdown of ZFAS1 remarkably improved cardiac function via decreasing infarction ratio and increasing vWF expression, left ventricular ejection fraction, and left ventricular fractional shortening compared with group MI. Knockdown of ZFAS1 also suppressed Wnt/ß-catenin pathway in vivo. The inhibition of Wnt/ß-catenin remarkably reversed the influence of shZFAS1 on cardiac function and cardiac fibroblasts viability. Therefore, Knockdown of ZFAS1 could improve the cardiac function of myocardial infarction rats via regulating Wnt/ß-catenin signaling pathway. The present study might provide new thoughts for the prevention and treatment of MI damage.